The use of the StackMatch to combine the antennas in phase delivers more gain, up 3 dB in the case of two antennas compared to a single one. But even more important is the coverage of the angles with the resultant lobes obtained with three different combinations. These different lobe angles will cover the variation of the incoming waves angles which depend on the varying ionospheric propagation conditions.

Low angle lobes are good for long-haul contacts specially at dusk and down while high angle lobes are better near local noon along the propagation path.